TWI690983B - Wafer processing method - Google Patents

Abstract

Provide wafer processing methods that can suppress the occurrence of foreign objects.

The wafer processing method is formed by InP A method of performing laser processing along a scribe line on a plurality of regions where the plurality of scribe lines on the surface of the formed substrate are divided into a plurality of regions, and the wafers with bumps formed thereon. The processing method of the wafer includes: the process of holding the wafer (ST1); the protective film forming process of forming a water-soluble protective film on the surface of the wafer (ST2); the laser light is irradiated to the wafer along the scribe line Irradiation process (ST3); after the laser light is irradiated, the wafer is cleaned to remove the protective film (ST4); and after the cleaning process (ST4), by the laser light irradiation process (ST3) The phosphorus-containing reaction product generated by the laser processing section will vaporize and react with the moisture in the air to form a phosphorus-containing foreign object on the bump. After the cleaning process (ST4) and after a predetermined time, the foreign object Removal of foreign materials removed (ST6).

Description

Wafer processing method

The invention relates to a wafer processing method.

In general, when manufacturing a device, multiple chip regions (planned dividing lines) arranged on the surface of the wafer in a grid shape are used to divide the multiple chip regions, and IC (Integrated Circuit) is formed in the chip regions. Body circuit), LSI (Large Scale Integration, large integrated circuit) and other components. When dividing these elements, laser processing is performed by irradiating laser light along the scribe lines of the wafer to form laser processing grooves on the surface of the wafer.

In this type of laser processing, when irradiated with laser light, fine dust called debris is generated/scattered and accumulates on the surface of the device, deteriorating the quality of the device. Therefore, a processing method has been proposed in which a protective film is pre-applied on the surface of a wafer, laser processing is performed, and debris adhering to the protective film is washed and removed together with the protective film (see, for example, Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-012508

However, in a wafer in which a substrate is formed of a phosphorus compound and metal electrodes such as bumps are provided on the surface of an element, elements (for example, phosphorus) that constitute the wafer by laser processing are freed/diffused. The diffused element system revealed that after the protective film was washed and removed, it reacted with nitrogen, oxygen, or moisture in the air to generate foreign matter on the metal electrode. Since this foreign material degrades device characteristics such as electrical characteristics, it is preferably removed quickly. However, since the generation rate of foreign matter is slow, it is difficult to remove the foreign matter at the same time as the protective film when washing the protective film. In addition, even if the foreign matter system changes the laser processing conditions and the composition of the protective film that covers the surface of the element during laser processing, the generation of foreign matter cannot be sufficiently suppressed.

The present invention has been completed in view of the situation shown above, and its object is to provide a wafer processing method that can suppress the occurrence of foreign matter.

In order to solve the above-mentioned problems and achieve the objective, the wafer processing method of the present invention is to form a device and a plurality of regions divided by a plurality of scribe lines formed on the surface of a substrate made of a phosphorus compound in a lattice shape The metal electrode wafer, a wafer processing method for laser processing along the cutting path, which includes: a process of holding the wafer with a chuck table; A protective film forming process of forming a water-soluble protective film on the surface of the wafer; after the protective film forming process is implemented, a laser light irradiation process of irradiating the wafer with laser light along the scribe line; performing the laser light irradiation After the process, the wafer is cleaned to remove the protective film; and after the cleaning process, the phosphorous-containing reaction product generated in the laser processing section by the laser irradiation process is gaseous It reacts with moisture in the air to form phosphorus-containing foreign materials on the metal electrode, and after the washing process and after a predetermined time has passed, the foreign material removal process of removing the foreign materials.

Preferably, in the foreign matter removal process, the surface of the wafer is washed with water to remove the foreign matter.

Or preferably, in the foreign matter removal process, the wafer is immersed in water to remove the foreign matter.

Or preferably, in the foreign matter removal process, the wafer is etched to remove the foreign matter.

The wafer processing method of the present invention is a simple method that sufficiently suppresses the foreign matter generated on the substrate after laser processing, so that the device characteristics can be maintained well.

1‧‧‧Laser processing device

2‧‧‧device body

10‧‧‧Sucker table

20‧‧‧Laser light irradiation department

21‧‧‧Oscillator

22: Concentrator

30: Cartridge

40: Temporary Department

41: Moving in and out

42: rail

50: Protective film formation and cleaning section

51: Rotating table

51a: suction cup

52: Electric motor

53: Ministry of Water Resources

53a: outer side wall

53b: Inner side wall

53c: bottom wall

53c1: Drain port

53d: Drain hose

55: Resin liquid supply nozzle

56: Air nozzle

57: Washing water nozzle

61: The first means of transportation

62: Second transportation means

100: washing device

AS: foreign body

BP: bump (metal electrode)

D: Components

F: ring frame

L: cutting path

LB: Laser light

LR: liquid resin

P: protective film

PD: Laser processing groove

PR: processing area

RW1: Wash water

RW2: Wash water

ST1: Engineering to keep wafers

ST2: Protective film formation project

ST3: Laser light irradiation project

ST4: Cleaning project

ST6: Foreign material removal project

T: Adhesive tape

TR: Move in and out of the area

W: Wafer

WS: substrate

FIG. 1 is a perspective view of a wafer which is a processing object of the wafer processing method of this embodiment.

FIG. 2 is a side view of the main part of the wafer shown in FIG. 1.

FIG. 3 is a perspective view showing a configuration example of a laser processing apparatus.

4 is a perspective view showing a configuration example of a protective film forming and cleaning section of the laser processing apparatus shown in FIG. 3.

FIG. 5 is a flowchart showing the sequence of the wafer processing method of the embodiment.

FIG. 6 is a cross-sectional view illustrating the process of holding a wafer.

7 is a cross-sectional view illustrating a protective film forming process.

FIG. 8 is a cross-sectional view of the protective film forming process.

9 is a cross-sectional view illustrating a laser light irradiation project.

Fig. 10 is a cross-sectional view of the laser beam irradiation project.

11 is a cross-sectional view illustrating the main part of the wafer in the laser light irradiation process.

Fig. 12 is a cross-sectional view illustrating the washing process.

FIG. 13 is a plan view illustrating a state in which foreign matter is generated on the bump surface after the washing process.

Fig. 14 is a cross-sectional view illustrating a foreign matter removal process.

Fig. 15 is a cross-sectional view illustrating a foreign matter removal process according to a modification of the embodiment.

The embodiment (embodiment) for implementing the present invention will be described in detail while referring to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, among the components described below Including those who are familiar with the technology in this field can easily think of, those who are substantially the same. In addition, the configuration systems described below can be combined as appropriate. In addition, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

With reference to the drawings, the wafer processing method of the embodiment will be described. FIG. 1 is a perspective view of a wafer which is a processing object of the wafer processing method of this embodiment, and FIG. 2 is a side view of the main part of the wafer shown in FIG. 1. As shown in FIG. 1, the wafer (workpiece) W is a semiconductor wafer or an optical element wafer having a disk-shaped substrate WS. In addition, the wafer W-based substrate WS is composed of indium phosphide (InP; phosphorus compound). As shown in FIGS. 1 and 2, the wafer W is formed with a plurality of streets L in a lattice shape on the surface of the wafer W, and elements D are formed in the plurality of regions divided by the plurality of streets L, respectively. . In addition, the element D of the wafer W is formed with a plurality of bumps BP (corresponding to metal electrodes) formed by protruding from the surfaces of the element D, respectively. The bumps BP are formed of precious metals such as gold (Au) or platinum (Pt). However, the number, position, and size of the bumps BP formed in each element D are not limited to those shown in FIG. 1. If the surface is exposed on the element D for placement, the shape, position, and size of the bumps BP may be appropriate. change. In the embodiment, the bump BP is shown as an example of the metal electrode. However, in the present invention, an electrode formed on the same plane as the surface of the element D may be used as the metal electrode.

FIG. 3 is a diagram showing a configuration example of a laser processing apparatus used in the wafer processing method of the embodiment, and FIG. 4 is a configuration example of a protective film forming and cleaning section of the laser processing apparatus shown in FIG. 3. Oblique view. However, the laser processing apparatus 1 is not limited to the configuration example shown in FIG. 3. The laser processing device 1 forms a water-soluble protective film P (hereinafter only referred to as a protective film P) on the surface of the wafer W, and then irradiates laser light along the scribe line L of the wafer W to form a laser processing groove PD (Shown in Figure 11). Next, the laser processing apparatus 1 removes the protective film P from the surface of the wafer W after laser processing.

As shown in FIG. 3, the laser processing apparatus 1 includes a chuck table 10 and a laser light irradiation unit 20. The laser processing apparatus 1 is additionally provided with: a cassette elevator (not shown) for placing a cassette 30 that houses wafers W before and after laser processing; and temporary placement of wafers W before and after laser processing Section 40; and the wafer W before the laser processing forms a protective film P, and the protective film P is removed from the wafer W after the laser processing to form a protective film and cleaning section 50. Moreover, the laser processing apparatus 1 is equipped with the X-axis movement means (not shown) which moves the chuck table 10 and the laser light irradiation part 20 in the X-axis direction relatively, and makes the chuck table 10 and the laser light irradiation part 20 Y Y-axis movement means (not shown) for relative movement in the axial direction; and Z-axis movement means (not shown) for relative movement of the chuck table 10 and the laser light irradiation unit 20 in the Z-axis direction.

The chuck table 10 holds the wafer W on which the protective film P is formed while performing laser processing. The chuck table 10 is formed of porous ceramics or the like to form a portion of a disk that constitutes the surface, is connected to a vacuum suction source (not shown) through a vacuum suction path (not shown), and absorbs the wafer W placed on the surface To hold the wafer W. The chuck table 10 is provided by X-axis movement means to move in and out the area TR and the laser around the cassette 30 The processing area PR near the light irradiation section 20 is freely movable in the X-axis direction, and is configured to be freely movable in the Y-axis direction by means of Y-axis movement, and is set around the central axis by a base driving source (not shown) (Parallel to the Z axis) Free rotation.

The laser light irradiation unit 20 is provided in the processing area PR provided in the apparatus body 2 and irradiates the surface of the wafer W held on the chuck table 10 with laser light LB (shown in FIG. 9) to form a laser processing groove PD. The laser light LB is a laser light having a wavelength that absorbs the wafer W. The laser light irradiation unit 20 sets the wafer W held on the chuck table 10 so as to be movable in the Z-axis direction by the Z-axis movement means. The laser light irradiation unit 20 includes an oscillator 21 that oscillates the laser light LB, and a condenser 22 that condenses the laser light LB oscillated by the oscillator 21. The oscillator 21 appropriately adjusts the frequency of the laser light LB to be oscillated in accordance with the type and processing form of the wafer W. As the oscillator 21, for example, a YAG laser oscillator or a YVO laser oscillator can be used. The condenser 22 is configured to include a total reflection mirror that changes the traveling direction of the laser light LB oscillated by the oscillator 21, a condenser lens that condenses the laser light LB, and the like.

The cassette 30 accommodates a plurality of wafers W attached to the ring frame F through the adhesive tape T. The cassette elevator is provided on the device body 2 of the laser processing device 1 so as to be able to move up and down in the Z-axis direction.

The temporary portion 40 takes out one wafer W before laser processing from the cassette 30 and stores the wafer W after laser processing in the cassette 30. The temporary part 40 is configured to include: before the laser processing is taken out from the cassette 30 The wafer W after the laser processing, and the carrying-in/out means 41 for inserting the wafer W after the laser processing into the cassette 30; and a pair of rails 42 for temporarily mounting the wafer W before and after the laser processing.

The protective film forming and cleaning unit 50 is a wafer W before laser processing on a pair of rails 42 that is carried by the first conveying means 61, and the protective film P is formed on the wafer W before laser processing . In addition, the protective film forming and cleaning unit 50 is carried by the laser processing wafer W by the second transfer means 62, and the protective film P of the laser processing wafer W is removed. The first and second transfer means 61 and 62 are respectively configured to be capable of sucking and lifting the surface of the wafer W, and lift and transport the wafer W to a desired position.

As shown in FIG. 4, the protective film forming and cleaning unit 50 includes a rotary table 51 that holds the wafer W before and after laser processing; and the rotary table 51 is rotated around an axis parallel to the Z-axis direction The electric motor 52; and the water receiving portion 53 arranged around the turntable 51. The turntable 51 is provided with a suction chuck 51a formed in a disc shape and made of porous ceramics or the like at the center of the surface (upper surface). The suction chuck 51a communicates with suction means (not shown). Thereby, the turntable 51 holds the wafer W by attracting the wafer W mounted on the suction chuck 51a.

The electric motor 52 is connected to the turntable 51 at the upper end of its drive shaft 52a, and rotatably supports the turntable 51. The water receiving portion 53 includes a cylindrical outer side wall 53a and an inner side wall 53b, and a bottom wall 53c connecting the outer side wall 53a and the inner side wall 53b, and is formed in a ring shape. The water receiving portion 53 receives the supply when the protective film P is formed on the surface of the wafer W The remaining amount of the liquid resin LR (shown in FIG. 7) supplied to the surface, or the washing water RW1 (shown in FIG. 12) supplied to the surface when the protective film P on the surface is washed and removed . The bottom wall 53c is provided with a drain port 53c1, and a drain hose 53d is connected to the drain port 53c1.

In addition, the protective film forming and cleaning unit 50 includes: a resin liquid supply nozzle 55 for supplying the water-soluble liquid resin LR constituting the protective film P to the wafer W held on the rotating table 51; The wafer W after the laser processing is supplied with the rinse water nozzle 57 for the rinse water RW1; and the wafer W supplied with the liquid resin LR on the turntable 51 and the wafer W after the cleaning are supplied with air Air nozzle 56. The resin liquid supply nozzle 55, the air nozzle 56, and the washing water nozzle 57 are respectively configured to move freely at an operating position where the nozzle opening is located above the center of the turntable 51 and a retreat position away from the turntable 51.

The resin liquid supply nozzle 55 is not shown, and is connected to a liquid resin supply source and a supply source. For the water-soluble liquid resin LR, water-soluble resin materials such as PVA (polyvinyl alcohol), PEG (polyethylene glycol), or PVP (polyvinylpyrrolidone) are used. The liquid resin LR is dried and cured to form a protective film P on the surface of the wafer W to protect the surface.

In addition, the washing water nozzle 57 is connected to a washing water (for example, pure water) supply source (not shown). The air nozzle 56 is connected to a dry air supply source (not shown), blows dry air to the liquid resin LR supplied on the rotary table 51, and dry the liquid resin LR to form a protective film P, and wash The cleaned wafer W blows dry air to dry the wafer W.

However, as described above, the wafer W-based substrate WS of this embodiment is a wafer formed of indium phosphide (InP: phosphorus compound), and a plurality of bumps BP (metal electrodes) are formed on the surface of the element D, respectively. When this type of wafer W is subjected to laser processing, the element (P (phosphorus) in this embodiment) constituting the wafer W is released (vaporized) from the processing surface of the wafer W exposed by the laser processing ) While spreading. After washing and removing the protective film P, the diffused phosphorus system reacts with nitrogen, oxygen, or moisture in the air to form a foreign substance AS containing phosphoric acid (H ₃ PO ₄ ) on the bump BP (shown in FIG. 13). The foreign matter AS system degrades the characteristics of the element D such as electrical characteristics, so it is better to remove it quickly. However, since the generation rate of foreign matter AS is slow (e.g., occurs in 2 or 3 days), it is difficult to wash the protective film P with The protective film P also removes foreign matter AS.

The wafer processing method of this embodiment is characterized in that the generation of phosphorus-containing foreign substances AS that may be generated on the surface of the element D (especially the bump BP) is suppressed.

Next, the wafer processing method according to the embodiment of the present invention will be described. FIG. 5 is a flowchart showing the sequence of the wafer processing method of the embodiment, FIG. 6 is a cross-sectional view illustrating the process of holding the wafer of the wafer processing method of the embodiment, and FIG. 7 is a wafer of the embodiment. The cross-sectional view of the protective film forming process of the processing method. FIG. 8 is a cross-sectional view of the wafer after the protective film forming process of the wafer processing method of the embodiment, and FIG. 9 is a cross-sectional view of the wafer processing method of the embodiment. Fig. 10 is a cross-sectional view of a laser light irradiation process. Fig. 10 is a cross-sectional view of a wafer etc. after a laser light irradiation process for explaining a wafer processing method of the embodiment, and Fig. 11 is a description of the embodiment FIG. 12 is a cross-sectional view of the main part of the wafer in the laser irradiation process of the wafer processing method. FIG. 12 is a cross-sectional view illustrating the cleaning process of the wafer processing method of the embodiment, and FIG. 13 is a crystal of the embodiment. FIG. 14 is a cross-sectional view illustrating the foreign matter removal process of the wafer processing method of the embodiment, after the cleaning process of the circle processing method generates foreign objects on the bump surface.

The processing method of the wafer is a processing method of performing laser processing on the wafer W along the scribe line L. As shown in FIG. 5, it includes: a process ST1 for holding the wafer W, a protective film formation process ST2, and a laser light irradiation process ST3, cleaning engineering ST4, and foreign material removal engineering ST6. First, in a wafer processing method, an adhesive tape T is attached to the back surface of a wafer W having a plurality of elements D formed on the surface, and an annular frame F is attached to the adhesive tape T. Next, the wafer W attached to the ring frame F through the adhesive tape T is housed in the cassette elevator.

Next, in the wafer processing method, the operator registers the processing content information in the control means of the laser processing apparatus 1. If the operator has an instruction to start the processing operation, the laser processing apparatus 1 starts the processing operation, that is, Wafer processing method. In the wafer processing method, first in the process ST1 that holds the wafer W, the control means is to carry out the wafer W before laser processing by the carrying in/out means 41 from the cassette elevator to the temporary portion 40, and load It is placed on the pair of rails 42 of the temporary part 40. After that, the control means is transferred to the turntable 51 of the protective film forming and cleaning unit 50 by the first transfer means 61, and as shown in FIG. 6, the wafer W is held on the turntable 51. Proceed to protective film formation process ST2.

Next, in the protective film formation process ST2, the control means forms the protective film P on the surface of the wafer W. Specifically, as shown in FIG. 7, the control means arranges the nozzle opening of the resin liquid supply nozzle 55 above the center of the wafer W, and supplies the nozzle with the resin liquid while rotating the turntable 51 at a predetermined number of rotations. 55 Water-soluble liquid resin LR (for example, PVA (polyvinyl alcohol)) is supplied to the wafer W. The supplied liquid resin LR expands radially outward from the center of the wafer W by the centrifugal force accompanying the rotation of the rotary table 51, so that a protective film P with a uniform film thickness can be formed. The control means supplies the liquid resin LR for a predetermined time, and after curing, the nozzle opening of the resin liquid supply nozzle 55 is retracted from above the wafer W. As a result, as shown in FIG. 8, the protective film P is formed on the surface of the wafer W. Proceed to laser beam irradiation project ST3.

Next, in the laser light irradiation process ST3, the control means irradiates the wafer W with laser light LB along the scribe line L. Specifically, the control means transfers the wafer W onto the chuck table 10 by the second conveying means 62 on the rotating table 51 of the protective film forming and cleaning unit 50, and attracts and holds the wafer W on the chuck table 10 on the surface of wafer W. Next, the control means moves the chuck table 10 by the X-axis movement means and the Y-axis movement means, rotates the chuck table 10 about the central axis by the base driving source, and irradiates the laser light by the Z-axis movement means The section 20 moves to position one end of the predetermined cutting lane L directly below the condenser 22. Next, as shown in FIG. 9, the control means is to irradiate the laser light LB from the condenser 22 of the laser light irradiation unit 20 while the chuck table 10 holding the wafer W is directed to the laser light by X-axis movement means. Irradiation section 20, along a predetermined cutting path L, move at a predetermined processing speed.

As a result, a part of the substrate WS and the protective film P of the wafer W are sublimated, and as shown in FIG. 11, by laser ablation processing, the laser processing groove PD is formed on the predetermined scribe line L to which the laser light LB is irradiated. As shown in FIG. 10, the control means stops the irradiation of laser light LB from the laser light irradiating section 20 as soon as the other end of the predetermined cutting lane L reaches directly below the condenser 22, and stops the X-axis movement means The resulting movement of the chuck table 10. The control means is to sequentially irradiate the laser light LB to the scribe lanes L to form laser processing grooves PD on the scribe lanes L, and to form the laser processing grooves PD on the full-section scribe lanes L of the wafer W . Proceed to washing project ST4.

Next, in the cleaning process ST4, after the laser light LB is irradiated, the control means cleans the wafer W to remove the protective film P. Specifically, the control means transfers the laser-processed wafer W from the chuck table 10 to the rotating table 51 of the protective film forming and cleaning unit 50 again from the chuck table 10 by the second transfer means 62. Next, the control means holds the wafer W on the suction chuck 51a of the rotary table 51, and as shown in FIG. 12, the nozzle opening of the cleaning water nozzle 57 is arranged above the center of the wafer W, and the rotary table 51 is scheduled to In a state where the number of rotations is rotated, the washing water nozzle 57 supplies the washing water RW1 made of pure water to the wafer W for a predetermined time. In this way, the protective film P is formed by drying the water-soluble liquid resin LR. Therefore, by supplying the cleaning water RW1 toward the protective film P, the protective film P is dissolved in the cleaning water RW1 and the wafer W The surface is removed. At this time, the debris generated by the laser processing is removed from the surface of the wafer W together with the protective film P. The control means supplies the washing water RW1 at a predetermined time After that, the nozzle opening of the washing water nozzle 57 is retracted from above the wafer W, and instead, the nozzle opening of the air nozzle 56 is arranged above the center of the wafer W, and the dry air is supplied by the air nozzle 56 for a predetermined time, thereby The surface of the wafer W is dried. However, in the present invention, in the washing process ST4, the control means may supply the washing water RW1 and the dry air from the nozzle opening while swinging the washing water nozzle 57 and the air nozzle 56.

Next, the control means stores the wafer W that has been laser-processed and cleaned in the cassette 30 by the first transfer means 61 and the transfer-in/out means 41. The control means is executed in order: the process ST1 of all wafers W held in the cassette 30, the protective film formation process ST2, the laser light irradiation process ST3, and the cleaning process ST4, and is housed in the cassette 30. If all the wafers W in the cassette 30 are laser-processed and cleaned, the operator removes the cassette 30 from the cassette elevator, and transports it to the storage place, where it is stored in the storage place. Next, the operator determines whether the predetermined time has passed after the washing process ST4 in the storage place (step ST5). Here, the so-called predetermined time is generated after the cleaning process ST4, by the laser light irradiation process ST3, in the laser processing section (including the laser processing groove PD and the vicinity of the laser processing groove PD) The reaction product containing the element (P (phosphorus) in this embodiment) constituting the wafer W vaporizes and reacts with nitrogen, oxygen, or moisture in the air to generate P( Phosphorus) The time taken for the foreign matter AS (phosphoric acid (H ₃ PO ₄ )) shown in FIG. 13. For example, the predetermined time is 2 or 3 days, but it is not limited to this.

If the operator determines that the predetermined time has not passed after the washing process ST4 (step ST5: No), step ST5 is repeated until the predetermined time passes. If the operator determines that a predetermined time has passed after the washing process ST4 (step ST5: Yes), as shown in FIG. 13, a foreign object AS is generated on the surface of the bump BP. Proceed to the foreign material removal project ST6.

The foreign matter removal process ST6 is a process of washing the process ST4 and removing the foreign matter AS after a predetermined time has passed. The foreign material removal process ST6 uses the cleaning device 100 having the same configuration as the protective film forming and cleaning unit 50. Here, the configuration of the cleaning device 100 is the same as the configuration of the protective film forming and cleaning section 50 except that the resin liquid supply nozzle 55 is not provided, and therefore the description is omitted.

In the foreign material removal process ST6, the operating device or the operator takes out one wafer W from the cassette 30, transfers the taken wafer W to the rotary table 51 of the cleaning apparatus 100, and holds the wafer on the rotary table 51 W. As shown in FIG. 14, the cleaning apparatus 100 arranges the nozzle opening of the cleaning water nozzle 57 above the center of the wafer W, and rotates the turntable 51 at a predetermined number of rotations. The wafer W is supplied with clean water RW2 made of pure water for a predetermined time. In this way, since the phosphoric acid (H ₃ PO ₄ ) constituting the foreign substance AS is water-soluble, the washing water RW2 is supplied to the foreign substance AS, whereby the foreign substance AS is dissolved in the washing water RW2 and passes from the surface of the wafer W Was removed. In the embodiment, the washing water RW2 made of pure water is used, but it is not limited to this. As described above, in the embodiment, in the foreign material removal process ST6, the surface of the wafer W is washed with water (pure water) to remove the foreign material AS. In addition, in the embodiment, the washing water RW2 made of a corrosive etchant that is acidic or alkaline may be used. At this time, the foreign matter AS is dissolved in the washing water RW2 as an etching solution and removed. At this time, in the foreign material removal process ST6, the surface of the wafer W is etched to remove the foreign material AS.

After the cleaning device 100 supplies the cleaning water RW2 for a predetermined time, the nozzle opening of the cleaning water nozzle 57 is withdrawn from above the wafer W, and instead, the nozzle opening of the air nozzle 56 is arranged above the center of the wafer W The dry air is supplied by the air nozzle 56 for a predetermined time, thereby drying the surface of the wafer W. However, in the present invention, in the foreign material removal process ST6, the control means may supply the washing water RW2 and the dry air from the nozzle opening while swinging the washing water nozzle 57 and the air nozzle 56. In the cleaning device 100, if the cleaning water RW2 made of an etching solution is used, it is preferable to supply the cleaning water RW1 made of pure water and then dry the wafer W after supplying the cleaning water RW2.

Next, the working device or the operator stores the wafer W from which the foreign matter AS has been removed in the cassette 30. If the operating device or the operator similarly removes foreign objects AS from the wafer W in the cassette 30, the wafer processing method is ended. Next, the wafer W is transferred to the next process, and is divided along the laser processing groove PD formed by the ablation processing, thereby being divided into individual devices D.

According to the wafer processing method of the embodiment, after the washing process ST4, after the time required to sufficiently generate the foreign matter AS on the bumps BP, the washing water RW1 is supplied to the surface of the wafer W, and Foreign matter removal process ST6 for removing foreign matter AS. In addition, the wafer processing method is to supply pure water as washing water RW1 in the foreign material removal process ST6. Therefore, the processing method of the wafer is composed of water-soluble phosphoric acid (H ₃ PO ₄ ) to constitute the foreign body AS, so the simple method of supplying the washing water RW1 can sufficiently remove the substrate of the wafer W after laser processing The foreign body AS that occurred in WS. As a result, the wafer processing method can effectively suppress the occurrence of foreign objects AS on the surface of the device D, and can maintain the characteristics of the device D well.

In addition, the wafer processing method is to perform the foreign material removal process ST6 after a predetermined time when the reaction product generated during the laser light irradiation process ST3 sufficiently reacts with water in the air and the like to generate the foreign material AS, so once the Removal of foreign matter AS can suppress the regeneration of foreign matter AS. As a result, the wafer processing method can effectively suppress the occurrence of foreign objects AS on the surface of the device D, and can maintain the device characteristics well. In addition, the wafer processing method is to etch the wafer W to remove the foreign matter AS. Since the washing water RW2 formed by the etching solution used in etching is corrosive, the need for the foreign matter removal process ST6 can be suppressed time.

Next, a wafer processing method according to a modification of the embodiment will be described with reference to the drawings. 15 is a cross-sectional view illustrating a foreign matter removal process of a wafer processing method according to a modification of the embodiment. However, in FIG. 15, the same parts as those in the embodiment are denoted by the same symbols and their description is omitted.

The wafer processing method of the modified example of the embodiment is the same as the embodiment except for the foreign material removal process ST6. In the foreign material removal process ST6 of the wafer processing method according to the modification of the embodiment, after the wafer W is held by the rotary table 51, the cleaning apparatus 100 opens the nozzle of the cleaning water nozzle 57 as shown in FIG. Arranged above the center of the wafer W, it is not necessary to rotate the rotary table 51, that is, the cleaning water nozzle 57 supplies the predetermined amount of the cleaning water RW2 made of pure water to the wafer W. In this way, as shown in FIG. 15, the washing water RW2 is accumulated inside the ring frame F, and the wafer W is immersed in the washing water RW2 already accumulated inside the ring frame F. Since the phosphoric acid (H ₃ PO ₄ ) constituting the foreign substance AS is water-soluble, the wafer W is immersed in the washing water RW2, and the foreign substance AS is dissolved in the washing water RW2 to be removed from the surface of the wafer W. In the modification, pure water is used as the washing water RW2, but it is not limited to this. As shown above, in the modification, in the foreign material removal process ST6, the wafer W is immersed in water (pure water) to remove the foreign material AS. After that, the cleaning apparatus 100 supplies the cleaning water RW1 to the wafer W for a predetermined time by the cleaning water nozzle 57 in a state where the rotary table 51 is rotated at a predetermined number of rotations, and the wafer W is cleaned by air The nozzle 56 supplies dry air for a predetermined time, thereby drying the surface of the wafer W.

According to the wafer processing method of the modification of the embodiment, the foreign material AS is composed of phosphoric acid (H ₃ PO ₄ ) which is water-soluble. Therefore, in the simple method of supplying the washing water RW2, the laser light can be sufficiently removed. Foreign matter AS generated on the substrate WS of the processed wafer W. As a result, the wafer processing method can effectively suppress the occurrence of foreign objects AS on the surface of the device D, and can maintain the characteristics of the device D well.

Next, the inventors of the present invention confirmed the effect of the wafer processing method of the embodiment. The results are shown in Table 1.

In Table 1, the product of the present invention is the wafer processing method of the embodiment. In Comparative Example 1, after a predetermined period of time (for example, 2 to 3 days) after the laser light irradiation process ST3, without performing the cleaning process ST4 without removing the protective film P, the cleaning process ST4 is performed and the protection is removed Membrane P. In Comparative Example 2, after the laser light irradiation process ST3, a cleaning process ST4 is performed, and the surface of the element D is directed downward for a predetermined time (for example, 2 to 3 days). Both Comparative Example 1 and Comparative Example 2 did not perform the foreign material removal process ST6.

According to Table 1, both Comparative Example 1 and Comparative Example 2 generate foreign objects AS on the surface of the bump BP. In contrast to these, the strain of the present invention does not generate foreign matter AS on the surface of the bump BP. It can be seen from Table 1 that after the washing process ST4, after the time required to sufficiently generate the foreign matter AS on the bump BP, the foreign matter removal process of supplying the washing water RW1 to the surface of the wafer W to remove the foreign matter AS ST6 can thereby suppress the generation of foreign matter AS on the surface of the bump BP.

However, the present invention is not limited to the above-mentioned embodiments and modifications. That is, it can be implemented with various modifications without departing from the framework of the present invention. For example, when pure water is used as the washing water RW1, RW2 in the present invention, a chemical solution having an amine group may be added to the washing water RW1, RW2. The wafer processing method is to add a chemical solution (such as MEA (monoethanolamine)) with an amine group to the cleaning water RW1, RW2, the amine group of the monoethanolamine, and the phosphorus diffused by the laser processing groove PD React to produce a phosphorus-containing compound (for example, ammonium phosphate ((NH ₄ ) ₃ PO ₄ ). The compound (ammonium phosphate) is water-soluble and has a longer reaction (generation) time than phosphoric acid (H ₃ PO ₄ ) Therefore, the processing method of the wafer is to add a chemical solution with an amine group to the washing water RW1, RW2 to generate a phosphorus-containing compound (ammonium phosphate), thereby suppressing the production of phosphoric acid (H ₃ PO ₄ ) Foreign body AS.

For chemical solutions with amine groups, for example: PAA ((registered trademark) polyacrylamine), PEI (polyethyleneimine) and other polymer chemical solutions, MEA (monoethanolamine), TETA (triethylene glycol) Amine) and other so-called low-molecular chemicals, monoethylamine, diethylamine, diisopropylamine, monoethanolamine, 2-amine ethanol, diethanolamine, triethanolamine, pyridine, NN-dimethylformamide, N-2- Mepyrrolidine, or a mixture of two or more of these, or diluted with water.

Claims (4)

A wafer processing method in which a device and a wafer on which metal electrodes are formed are cut along a plurality of regions divided by a plurality of scribe lines formed on the surface of a substrate made of a phosphorus compound in a lattice shape A wafer processing method for laser processing includes: a process of holding the wafer with a chuck table; a protective film forming process of forming a water-soluble protective film on the surface of the wafer; implementing the protective film forming process Then, a laser light irradiation process that irradiates the wafer with laser light along the scribe line; after the laser light irradiation process is performed, the wafer is washed to remove the protective film; and the washing process After the net process, the phosphorus-containing reaction product generated in the laser processing section by the laser light irradiation process will vaporize and react with the moisture in the air to generate a phosphorus-containing foreign material on the metal electrode. After the washing process and after a predetermined time has passed, the foreign matter removal process of removing the aforementioned foreign matter. For example, in the wafer processing method of claim 1, the surface of the wafer is washed with water to remove the foreign matter in the foreign matter removal process. For example, in the method of processing a wafer according to item 1 of the patent application, in the foregoing foreign material removal process, the wafer is immersed in water to remove the foreign material. If the wafer processing method of the first item of patent scope is applied, its In the aforementioned foreign matter removal process, the wafer is etched to remove foreign matter.

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